Ok, I think the next game should be a tad darker, like SOMI but still very funny. Ok, heres the pitch:

LeChck gets blown away by the Ultimate insult back to Monkey Island, once he returns he discovers a voodoo formla for a potion that can case living pirates to become undead zombie pirates simply by contact with someone who has been infected. This causes everyone in the Tri Island area to start becoming ndead zombie pirates and spreding their sickness untill everyone becomes a slave to LeChck and he can rule the Carribean and make Elaine is willing bride and rid himself of Guybrsh Threepwood. Well, As Guybrsh and Elaine are sailing arond they are boarded by LeCheck's new undead pirates and Elaine becomes infected. Guybrush insult sword fightes their asses of his boat and locks Elaine up tight. Guybrush sails to Melee island to get help from the voodoo lady. She tells him that a combination a voodoo supplys (ex. peant butter, nose hair and face paint) can form and antidote which can cure the living dead and bring them back to life. Guybrush uses it on Elaine then they work together to find enough so everyone can be cured. It is then stapped to a rocket and exploded in the sky which causes it to rain down and cure everyone. Guybrsh then sails to Monkey Island and uses the cure on LeChuck. LeChuck becomes alive again and Guybrush can then kill him for good or put him in jail or something. Also, Guybrsh solves the secret of Monkey Island but I have no idea what that should be. I know it sounds short and dorky but if LucasArts picked it up they could work with it. I personally think it would perfectly match the basic themes and stories of the first MI games

EMI isn't the first Monkey Island game.

Your story is far too EMI-like. It sounds like it belongs in a Sunday morning cartoon or something. EMI's plot was based around this silly/humour/cartoony theme, and that's one of the main reasons that it was a disappointment.

Monkey Island 1 and 2 alone have a rather serious plot. You could remove all the humour from the games and the plot would still be intact, especially if you consider the whole secret of Monkey Island thing that was discussed a long time ago on this board (about Guybrush actually being a kid in a pirate theme park).

Since EMI pretty much ruined any chance of there being another Monkey Island game that's good in the same ways as MI1 and MI2, I probably wouldn't like ANY idea for an EMI sequel. This is why I'd rather hear an idea for a sequel to Monkey Island 2 that ignores CMI and EMI.

Here's a sequel to Monkey Island 2:

Elaine and Herman go down the hole to see what happened to Guybrush.
Guybrush is on that bed in the medical room with all these pipes and things running in and out of him.
They set him free, and he wakes up from his nightmare state.
They don't understand why LeChuck hasn't killed Guybrush.
They leave Dinky Island on Elaines boat, and head to LeChucks fortress. Herman stays behind to 'guard' the entrance to Big Whoop.
The fortress is a ruin, and Largo is sat on some debris.
They tell Largo he can come on the boat and go to Booty if he tells them what is going on.
Largo agrees, but he double crosses them - he pushes Guybrush into the sea and sails off with Elaine as his prisoner.
I hate to say it, but I guess it's gotta be.... Wally is also in the debris.
He helps Guybrush to make a raft, and they sail off back towards Dinky. (Because they can't sail all the way back to the Booty, or anywhere, because they don't know where they are - only Elaine knew the way back, because she made it there in the first place.)
At Dinky Guybrush helps Wally to make a map, and so they can head off to find LeChuck.
When Guybrush is looking for the equipment (paper, ink etc) he finds Elaines ship hidden in a lake.
He returns to tell Herman and Wally, but they are gone.
Guybrush returns to the entrance to Big Whoop.
Largo is there, with Wally. Herman isn't around.
He follows Largo down, and sees him talking to someone, who sounds like LeChuck.
He sneaks in and finds Elaine in the back, tied up. She tries to warn him, but it's too late - Largo finds him.
Largo takes Guybrush to his master - its.... HERMAN!!
Herman points out that it's rather strange that whenever LeChuck is near, so is Herman - like on Monkey Island when Herman appears behind Guybrush in the catacombs.
Guybrush says it makes no sense, because Herman helped him get back to Melee.
Herman explains that he was a sailor who was shipwrecked on Monkey Island, and another ship was wrecked there - LeChuck's ship. LeChuck's spirit entered Herman, and could control him. Every once in a while, enough of the original Herman came through so that he could stop LeChuck from killing Guybrush.
Guybrush is tied up with Wally - LeChuck wants him to witness his marriage to Elaine before he kills him.
Guybrush escapes, and traps Largo in the Carnival of the damned (that'd be a helluva puzzle, putting him on the bed and everything.)
He then takes on Herman, and they fight.
Herman casts a voodoo spell and they are transported back to Monkey Island, in the catacombs where LeChuck has most power.
Just when Guybrush is about to be killed, the original Herman prevails, and throws himself into the lava.
LeChucks ghost returns, and runs away.
Guybrush goes to the cannibals and makes another anti-root thingamabob.
He kills LeChuck once and for all, and then sets off back to Melee in the rowing boat.
On the way back he meets Wally and Elaine, who escaped from Big Whoop.
The End - until the new MI4.
Post Script - we see Largo with his parents going around the Carnival of the Damned - he vows revenge on LeChuck and Guybrush.

Well, some points need refining I guess, but thats the basic plot.

I think LeChuck should be destroyed for good in a Monkey Island 2 sequel... And one thing it really needs: A sea monster. In fact, the plot could be based around a sea monster.